Gpg

GPG primer

Sources:

• https://davidwinter.dev/managing-gpg-with-keybase/: how to export keys to pgp.mit.edu et sim.
• https://github.com/pstadler/keybase-gpg-github: signed commits
• using-keybase-for-ssh-with-gpg-agent-on-macos: my starting resource, configure gpg-agent
• https://opensource.com/article/19/4/gpg-subkeys-ssh: big help with ~/.gnupg/sshcontrol
• How to use a GPG key for SSH authentication: great resumé on gpg-agent setup

Modify expiration date

$ gpg  --keyid-format SHORT  --list-keys francesco.malvezzi@unimore.it
pub   rsa4096/7635D5FA 2015-06-10 [SCA] [expires: 2025-06-07]
      E4D183BF57B5D0E4755651A703A5EB897635D5FA
uid         [ultimate] Francesco Malvezzi <francesco.malvezzi@unimore.it>
sub   rsa4096/2CED909F 2015-06-10 [E] [expires: 2025-06-07]

pub   rsa2048/B5B53BBB 2019-06-04 [SC] [expired: 2020-06-03]
      EFC2A973249908A6AF7BB31815C71F3CB5B53BBB
uid         [ expired] Francesco Malvezzi <francesco.malvezzi@unimore.it>

$ gpg --edit-key 7635D5FA
[...]
gpg> expire
[...]
gpg> key 1
gpg> expire
[...]
gpg> save

Modify key trust

$ gpg --edit-key 7635D5FA
[...]
Please decide how far you trust this user to correctly verify other users' keys
(by looking at passports, checking fingerprints from different sources, etc.)

  1 = I don't know or won't say
  2 = I do NOT trust
  3 = I trust marginally
  4 = I trust fully
  5 = I trust ultimately
  m = back to the main menu

Your decision? 5
Do you really want to set this key to ultimate trust? (y/N) y
[...]

Delete subkey

$ gpg --list-keys --with-subkey-fingerprints francescm@duck.com
gpg: checking the trustdb
gpg: marginals needed: 3  completes needed: 1  trust model: pgp
gpg: depth: 0  valid:   6  signed:   1  trust: 0-, 0q, 0n, 0m, 0f, 6u
gpg: depth: 1  valid:   1  signed:   0  trust: 1-, 0q, 0n, 0m, 0f, 0u
gpg: next trustdb check due at 2024-10-21
pub   rsa4096 2023-03-08 [SC] [expires: 2039-03-04]
      90A7D4C7EB237FE2C89E130E96C5E4735A1FB5EB
uid           [ultimate] Francesco Malvezzi <francescm@duck.com>
sub   rsa4096 2023-03-08 [E] [expires: 2039-03-04]
      8F082ED70AA3D378C34AE70468387D99570C7FF7
sub   rsa4096 2023-03-08 [A] [expires: 2039-03-04]
      79C413784C4223F844816EE9664E14874939DB59

$ gpg --delete-secret-and-public-keys 79C413784C4223F844816EE9664E14874939DB59!
[...]

Push your updated key to Keybase

   keybase pgp update

Ready to ssh-agent

You need to add the keygrip to `~/.gnupg/sshcontrol`.

   $ gpg2 -K --with-keygrip francescm@duck.com